A Short Introduction to Climate Change

Tony Eggleton’s A Short Introduction to Climate Change is an excellent account of climate science for the general reader. The author is a retired geology professor from the Australian National University. Two widely read climate change deniers, Ian Plimer and Bob Carter, are also retired Australian geology professors, but Eggleton is not of their ilk. He comes at the subject from a concern about climate change and a wish to explain to readers who are uncertain about the topic why there is reason for concern.

The book is grounded in the careful science which has contributed to our understanding of the danger in which we now stand. Eggleton has not worked in the field of climate, but recognises the authenticity of the findings of climatologists. His opening chapter, The Spirit of Enquiry, offers a clear account of the process by which science across all its fields advances. He highlights the fact that most climate science is done by groups, all of whom need to be confident of the reliability of their colleagues. He explains the rigorous process of peer reviewed papers and the comprehensive scrutiny from fellow scientists which follows their publication. He ponders the fact that some hypotheses are of the type that involves a choice between only two possibilities. If one is not true the other must be so. How will the theory of climate change caused by the burning of fossil fuels be viewed in 100 years from now? “Interpretations evolve, change and sometimes settle into accepted fact: the Sun is at the centre of the solar system, the continents have drifted and smoking does damage the lungs.”

The course the book follows is logically developed and well marked by summaries and frequent recapitulations. The evidence of warming is comprehensive: spring timing is earlier; winters are milder; land and sea surface and atmospheric temperatures are rising; extreme temperature events are more frequent. This warming is driving the fundamental climate change which underlies changes in weather, and it is caused by the increasing level of carbon dioxide in the atmosphere since 1750. Not that the author rushes to this conclusion. He leads the reader through all the thinking and observation which builds towards it, introducing a host of considerations such as the Milankovich cycles, the Keeling curve, water vapour, clouds, feedbacks and much else, all carefully explained.

The theme of climate change is pursued into all its manifestations in droughts and changed rainfall patterns, the loss of ice cover, the changes to the acidity of the world’s oceans and sea level rise. Again these are all patiently explored with frequent sourcing of the scientific findings to the work of particular scientists and their colleagues.

At this point Eggleton looks back in time, on geological time scales, detailing the lines of evidence from which the changes in temperature and CO2 and the eras of glaciation can be mapped out over the past 400 million-year period. “The connection between climate and CO2 is quite evident in the geological record, and that evidence – the coal, glacial drop-stones, types of shellfish fossils – tells us that when atmospheric CO2 falls, so does the temperature; when CO2 rises, so does the temperature.” More recently, over the past 2000 years, he notes the various studies which confirm Mann’s ‘hockey stick’, the rapid and now steepening rise in global temperature since 1800. He comments that what is special is not the temperature, nor even that it is changing, but rather the speed of the change. At its very fastest, at the end of the last ice age the world warmed at a rate of 1°C every 1000 years. “As far as palaeontology and geology can discover, temperature change as fast as 1.5°C a century has not happened in at least the past 2 million years; it has not happened over the time of Homo sapiens.” The ominous rapidity of the changes we are seeing is a recurring theme in the book.

Lest there be any uncertainty as to where the increased CO2 is coming from, the book traverses the evidence that it comes from the burning of fossil fuels and other human activities such as cement manufacturing and deforestation. The global carbon cycle receives attention here.

Before moving on to discuss what we can do to remedy the threatening imbalance we have caused Eggleton devotes a chapter to what he calls the road block – influential and vociferous people who deny that climate change is happening or is of any consequence. He imagines a reader asking why the body of science that surely underpins contrarian views has not been represented in this book. “The answer is because there is no such body of knowledge. I looked. I searched extensively.” He turns his attention to the two prominent retired Australian geologists, Plimer and Carter, who deny that warming is caused by the burning of fossil fuels, maintaining that if there is any current change in climate we must look to natural causes. Eggleton points out that climate scientist always include the natural causes of climate change in their research and that the burning of fossil fuels has augmented a process of natural climate variation. Plimer is wrong to deny that we can change the normal planetary processes. Eggleton is patient and exhaustive in his treatment of the views of the two geologists, not dismissive but thoroughly rebutting their claims.

What lies ahead? Eggleton’s tone in talking about the predictions is cautious and he certainly can’t be accused of overstatement. But as he explains the implications, and includes mention of the fears of scientists such as Hansen who are very aware of the possibility of runaway climate change, it is very clear that the risks for our grandchildren are very substantial indeed. His focus on what change is likely to mean for Australia is a valuable one for readers in this part of the world.

Finally he reaches the question of what we can do about it and begins by saying that whereas in the rest of the book he has been careful to report quality scientific results, he now moves beyond his scientific comfort zone. I found this short closing section less positive than much I have read on the ways in which we can switch to renewable energy if we have the mind to, but if that’s a flaw it’s a minor one in the context of the book as a whole.

The book takes an impressive body of science seriously and explains it thoroughly for the non-scientist reader. Although many commentators say inaction on climate change is not due to lack of understanding I continue to think that a grasp of the scientific reality by a wide sector of society is an essential element in our preparedness to recognise that there is a crisis and to address it.

The voice of reason may not always be listened to, but I don’t know where else hope lies. Eggleton’s presentation is marked by its reasonableness and one hopes many readers will be appreciative of that.

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